Centennial-scale variation in late Holocene planktonic foraminifer assemblages at Orphan Knoll, Labrador Sea.
Abstract
At a site located on the boundary between the Labrador Sea and the North Atlantic Drift, several species of planktonic foraminifer show peaks at ~250-300 yr intervals through the last 2800 yrs. This interval is near the 250 yr period that has been detected in global proxy temperature reconstructions and the 300 yr period that has been found in diatom assemblages and geochemical indicators in Icelandic coastal lakes. Previous faunal, isotopic and geochemical work has detected the bi-modal ``Little Ice Age" and a surface cooling event at 1600 yrs BP that corresponds to a similar event at Bermuda Rise. KN158-4-23MC is 33 cm long and was collected from a sediment drift on the east flank of Orphan Knoll. The high rate of sediment accumulation permits halving the sampling interval to 0.5 cm for current work, yielding a temporal resolution of 25-50 yrs. The centennial-scale oscillation is most apparent in most species present with an inverse relationship between subpolar and polar species. The Gulf Stream indicator species, Globoconella inflata, also shows centennial-scale variation with preceding those in the Neogloboquadrina pachyderma (s) record by ~50-100 yrs. Finally, there is a long-term trend in the record with subpolar Globigerina bulloides and Turborotalita quinqueloba dominating the >1500 yr BP interval and Neogloboquadrina pachyderma (s) and (d) dominating the <1500 yr BP interval.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFMPP21A0461C
- Keywords:
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- 1635 Oceans (4203);
- 3030 Micropaleontology;
- 4267 Paleoceanography;
- 4576 Western boundary currents;
- 4870 Stable isotopes